Earth science

Geologic time and carbon

Relative and absolute ages, the carbon cycle.

Basics

Dating

Lower beds are older (original horizontality, superposition; faults and intrusions come later). Fossils correlate. Radiometric ages use parent/daughter ratios. Half-life must fit the sample’s age.

Carbon cycle

Fast loop: photosynthesis, respiration, ocean uptake. Slow loop: weathering, burial, volcanoes. Fossil fuels open a slow store quickly. pH and temperature feed back.

Formulas

Radiometric age (sketch)

t = (1/λ) ln(1 + D/P)

Closed system, initial-daughter correction. P parent, D radiogenic daughter.

Symbols

P remaining parent
D radiogenic daughter

Key table

Phanerozoic	about 540 Myr — since hard fossils became common

In this field

Rocks and plate tectonics

Rock cycle, earthquakes, volcanoes, plate boundaries.

Atmosphere and weather

Layers, wind, clouds, fronts.

Oceans, climate, time

Currents, carbon, climate vs weather, relative and absolute age.

Minerals and water

Minerals and Mohs, water cycle, groundwater, soil.

Hazards and resources

Volcanoes, slides, storms; fuels and ores.

Weathering, soil, and the water cycle

Weathering, erosion, soil profiles, and the water cycle.

Earth’s magnetic field

The dynamo, the dipole, inclination and declination, paleomagnetism and seafloor stripes.

Glaciers and sea level

Glacier budget, isostasy, sea level, and glacial deposits.

Groundwater

Porosity, permeability, water table, Darcy, aquifers and aquitards.

Seismic waves

P, S, and surface waves, travel-time curves, magnitude, and Earth’s interior sketch.